Mode of finding the area of irregular figures



NITED STATES PATENT OFFICE.

THOS. WOOD, OF SMITHFIELD, OHIO.

MODE 0F FINDING THE AREA OF IRREG-ULAR FIGURES.

Speccation of Letters Patent No. 1,256, dated July 22, 1839.

To all whom t may concern.'

Be it known that I, THOMAS WOOD, of Smithfield, in the county of J elerson and State Of Ohio, have invented a new and useful Mode and Apparatus for Obtaining the Square or Rectangle of any Figure, Vhether Bounded by Right Lines, a Circle, or Ellipsis; and I do hereby declare that the following is a full and exact description.

The nature of my invention consists in cutting paper to a correspondin form and dimensions with an accurate p ot of the superfices to be measured and introducing it into astratum of mercury held between glass plates:

To enable others skilled in the art to make and use my invention I will proceed to describe its construction and operation.

I take two glass plates with plain ground surfaces and place between three of their margins card paper or any material that will keep their inner surfaces parallel and at a small distance apart, leaving the fourth side AB, (Figure l.) open. Then fasten them together with a frame C, C, C, of wood or metal and partly ill the rectangular space ABDE with pure mercury DEFG. I then cut a piece of paper to the size and shape of any plot, as the piece HI, bounded by the sides l, 2, 3, t, 5, &c., leaving one of its sides 17 attached to a rectangular piece FGJ K which should be as wide as t-he rectangular space ABDE between the glasses. I then draw the line HIL through the paper so as to bisect the rectangular piece J KFG parallel with its two sides JF and KG. Then, while the apparatus containing the mercury is held horizontal I slide the rectangular end of the paper into it until it makes the Outer edge of the mercury FG straight and mark its distance HL on the line HIL from the outer or open edge AB of the glasses. I then withdraw the paper, turn it around, and introduce the irregular pieces HI foremost (Fig. 2) sliding it gently until the displaced mercury surrounds it filling up all the irregular space A, A, A, A, and comes in contact with the side JK of the rectangular piece J FGK. Then the distance on the line I-IL of the outer edge JK of the mercury from the open edge AB of the apparatus subtracted from the distance I-IL (Fig. 1) will leave a distance equal to one side of a rectangle equal to the area of the plot introduced, which distance, multiplied by the width of the mercury on the line JK will give the area required, or HLXAB (Fig. 1)- MJ AB (Fig. 2):plot 1, 2, 3, et, 5, &c.. or the rectangle ABF G (Fig. 1) minus rectangle ABJK (Fig. 2) equals the area l, 2, 3, 4, 5, &c.

IVhat I claim as my invention and desire to secure by Letters Patent, is-

The application of the principle that solids introduced into iuids displace a quantity equal to their bulk7 to the mensuration of superices by means of mercury and glass plates as herein described.

THOS. IVOOD.

IVitnesses C. R. BOYER, J. HEINZELMAN. 

